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Assessment and selection of the recipient cows' corpus luteum at the time of embryo transfer, and its influence on conception rate
Author(s) -
Thomson SP,
Holmes RJ,
Landes PT,
Allworth MB
Publication year - 2021
Publication title -
australian veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.382
H-Index - 59
eISSN - 1751-0813
pISSN - 0005-0423
DOI - 10.1111/avj.13068
Subject(s) - corpus luteum , selection (genetic algorithm) , embryo transfer , embryo , andrology , biology , medicine , pregnancy , computer science , artificial intelligence , genetics
Objectives To describe the influence of physical traits of the corpus luteum (CL), as described by transrectal ultrasonography on day 6 post‐oestrus, on the conception rate following embryo transfer (ET) in recipient beef cows. To investigate if higher recipient utilisation rates were achievable, without compromising conception rates to ET. Design/Results Data were analysed from Holstein Friesian embryos (n = 1075) frozen in ethylene glycol thawed for direct transfer into one herd of Angus recipient cows. For pregnancies achieved in the program (n = 693), no statistically significant effect was found for the physical traits of the recipients' CL on conception rate (CL volume ( P = 0.20), CL side ( P = 0.14). Conception rates were similar for recipients with a central lacuna (62%, n = 245) and recipients with no central lacuna (66%, n = 448) ( P = 0.10) . Of the pregnant recipients with a central lacuna (n = 245), 98.3% had no remaining luteal cavity by the 30‐day pregnancy ultrasound. No effect on conception rate was found with either the small (<50% of CL diameter) or large (>50% of CL diameter) central lacunae ( P = 0.18). For recipients with CLs that did not meet previous industry selection guidelines (n = 172, 16% of study population), the conception rate (63%) was not significantly different to the routinely selected recipient CLs (n = 903, conception rate 65%) ( P = 0.83). Conclusions The suitability of a potential ET recipient is determined by observing an appropriately timed oestrus and a detectable CL, regardless of size or quality.